i would give it a day or 2.. give the mite spray time to work and see if he improves.. the vet will tell you this as well since i called the one here about my izzy swelling in the vent section and not being active at all...
imo if he eats and is nice n warm hes not gonna go down hill over night..
if he doesn't improve in a day or 2 then yeah ide call the vet